1. Field of the Invention
The present invention relates to a method of producing an electroluminescent element in which patterning of an organic electroluminescent (hereinafter, electroluminescent is abbreviated as EL in some cases) layer is conducted by using a layer in which a property changes by the action of a photocatalyst in irradiation with energy, the method being not influenced by the photocatalyst.
2. Description of the Related Art
In EL elements, holes and electrons injected from facing electrodes bond in a light emitting layer, excites a fluorescent substance in the light emitting layer by the energy, and emit light in color corresponding to the fluorescent substance, therefore, EL elements are attract to attention as a sheet display element of self light emitting type. Among them, organic thin film EL displays using an organic substance as a light emitting material, have high light emitting efficiency such as realizing of emission of high brilliance even if applied voltage is slightly less than 10 V, and the like, are capable of emitting light with a simple element structure, and there are expectations of application thereof to advertisement displays on which a specific pattern is emitted and displayed and to other low cost simple displays.
In production of displays using such EL elements, patterning of an organic EL layer and the like is usually conducted. As the method of patterning such EL elements, there are suggested a method in which a light emitting material is vapor-deposited via a shadow mask, a method of divisional coating by ink jet, a method of breaking a specific light emitting dye by irradiation with ultraviolet ray, various patterning methods such as a screen printing method and the like, however, there is also suggested a method of using a photocatalyst which enables easy formation of elaborate patterning.
These methods of producing an EL element using a photocatalyst utilize a phenomenon in which when a layer containing a photocatalyst is irradiated with energy, the wettability of the layer containing a photocatalyst varies due to the action of the photocatalyst in irradiation. Namely, by utilizing a pattern of this wettability difference, an organic EL layer is formed into a pattern. The method of producing an EL element using a photocatalyst like that is a useful method in that works required for patterning of an organic EL layer can be significantly reduced since a pattern of a wettability difference can be formed only by irradiation with energy.
However, such methods of producing an EL element using a photocatalyst have a problem that there is supposed a possibility of an influence, from a photocatalyst, on an EL element due to the semi permanent action of a photocatalyst contained inside, since a layer containing a photocatalyst is contained in the constitution of an EL element.